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I designed and built this thing many
years ago. I published the hobby circuit in the now defunct “Radio Elecronics” magazine
back in 1992. The electronic circuit injects a precise 1 amp of current into any unknown
resistor, up to about two ohms. Two alkaline C cells power the complete circuit. A
voltage booster provides the current control circuit with a higher voltage, to insure
the electronic circuit operates properly, even as the battery voltage drops. A single
LED provides both power monitoring and a low battery indicator. The current source is
activated when a pushbutton switch is pressed. |
